Hi，大家好，我是编程小6，很荣幸遇见你，我把这些年在开发过程中遇到的问题或想法写出来，今天说一说Java使用多数据源 方法配置[亲测有效],希望能够帮助你!!!。

首先需要引入druid连接池依赖 ，此处选择alibaba连接池

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.8</version>
</dependency>

配置数据源信息  可创建多个

spring：
  datasource:
    druid:
      #第一个数据库连接信息 local  
      local:
        type: com.alibaba.druid.pool.DruidDataSource
        username: root
        password: mima
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/local?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
      #第二个数据库连接信息 cloud
      cloud:
        type: com.alibaba.druid.pool.DruidDataSource
        username: root
        password: mima
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/cloud?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true

创建配类DataSourceConfig 注入配置信息

import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;


@Slf4j
@Configuration
public class DataSourceConfig {

    /**
     * 将cloud数据连接信息注入cloudDataSource
     */
    @Bean(name = "cloudDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.druid.cloud")
    public DataSource cloudDataSource(){
        return DruidDataSourceBuilder.create().build();
    }

    /**
     * 将local数据连接信息注入localDataSource
     */
    @Bean(name = "localDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.druid.local")
    public DataSource localDataSource(){
        return DruidDataSourceBuilder.create().build();
    }
}

创建DataSourceNames类 给数据源命名 便于使用。

public interface DataSourceNames {
    String cloudDataSource = "CLOUDDATASOURCE";
    String localDataSource = "LOCALDATASOURCE";
}

自定义注解DataSource 默认选中数据源 localDataSource 

import java.lang.annotation.*;

@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
    String value() default DataSourceNames.localDataSource;
}

创建 DynamicDataSource类 extends AbstractRoutingDataSource 重写determineCurrentLookupKey方法

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

import javax.sql.DataSource;
import java.util.Map;

public class DynamicDataSource extends AbstractRoutingDataSource {
    private static final ThreadLocal<String> CONTEXT_HOLDER= new ThreadLocal<>();

    /**
     * 配置DataSource, defaultTargetDataSource为主数据库
     */
    public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
        super.setDefaultTargetDataSource(defaultTargetDataSource);
        super.setTargetDataSources(targetDataSources);
        super.afterPropertiesSet();
    }

    @Override
    protected Object determineCurrentLookupKey() {
        return getDataSource();
    }

    public static void setDataSource(String dataSource) {
        CONTEXT_HOLDER.set(dataSource);
    }

    public static String getDataSource() {
        return CONTEXT_HOLDER.get();
    }

    public static void clearDataSource() {
        CONTEXT_HOLDER.remove();
    }
}

创建SqlSessionConfig

import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;


@Slf4j
@Configuration
public class SqlSessionConfig{
    @Bean(name = "dataSource")
    @Primary
    DataSource dataSource(@Qualifier("cloudDataSource") DataSource cloudDataSource , @Qualifier("localDataSource") DataSource localDataSource){
        Map<Object,Object> targetDataSources = new HashMap<>(2);
        targetDataSources.put(DataSourceNames.cloudDataSource,cloudDataSource);
        targetDataSources.put(DataSourceNames.localDataSource,localDataSource);
        log.info("DataSource:{}" + targetDataSources);
        return new DynamicDataSource(localDataSource,targetDataSources);
    }

    @Bean
    @Primary
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        //在yml文件中配置开启驼峰式命名转化时不生效，在此设置
        bean.getObject().getConfiguration().setMapUnderscoreToCamelCase(true);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*.xml"));
        return bean.getObject();
    }
}

配置切面 在使用自定义@DataSource注解时 将指定数据源注入

import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;

@Component
@Aspect
@Slf4j
public class DataSourceAspect {
    @Pointcut("@annotation(com.zhuodao.config.DataSource)")
    public void pointCut(){}

    @Around("pointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        MethodSignature signature = (MethodSignature) point.getSignature();
        Method method = signature.getMethod();
        DataSource dataSource = method.getAnnotation(DataSource.class);
        DynamicDataSource.setDataSource(dataSource.value());
        log.info("set dataSource is {}" , dataSource.value());
        try {
            return point.proceed();
        }finally {
            DynamicDataSource.clearDataSource();
            log.info("clearDataSource");
        }
    }
}

注解注入 在操作数据库时指定数据源 使用@DataSource()注解 示例如下

@Service
public class CloudTaskServiceImpl implements CloudTaskService {

    @Autowired
    private TaskMapper taskMapper;

    //注解注入
    @Override
    @DataSource(value = DataSourceNames.cloudDataSource)
    public int insertTask(Task task) {
        return taskMapper.insert(task);
    }
}

@Service
@Slf4j
public class LocalTaskServiceImpl implements LocalTaskService {
    @Autowired
    private TaskMapper taskMapper;

    @Override
    @DataSource //使用默认数据库
    public List<Task> selectAll() {
        log.info("task"+taskMapper.selectAll().size());
        return taskMapper.selectAll();
    }
}

在某些业务上，可能要操作多个数据库，那么使用注解在方法上注入数据源就不是那么的方便，所以就需要手动注入

手动注入 在操作数据库前使用DynamicDataSource.setDataSource("")方法 也可注入 示例如下

@Service
public class CloudTaskServiceImpl implements CloudTaskService {

    @Autowired
    private TaskMapper taskMapper;

    //手动注入 
    @Override
    public int insertTask(Task task) {
        DynamicDataSource.setDataSource("CLOUDDATASOURCE");
        return taskMapper.insert(task);
    }
}

可能会遇到的问题

切面方法不执行 需要加入aspectjrt， aspectjweaver依赖 ，缺一不可！

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.9.7</version>
        </dependency>

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.7</version>
        </dependency>

如果你恰好也有可以用多数据源实现的类似场景，希望对你有帮助。如有写的不对或不够好的地方，欢迎指正。

今天的分享到此就结束了，感谢您的阅读，如果确实帮到您，您可以动动手指转发给其他人。